Such appliances are well known and are in widespread use. They comprise a case having a handle and containing an electric motor which rotates a first end of a shaft included in a fixed tube or sleeve, with the tool being mounted at the other end of the shaft. The tool is driven at high speed and is plunged into food that is to be prepared, where the tool chops, blends, emulsifies, etc. the food.
The problem which arises with that type of appliance is essentially a problem of hygiene. Given the presence of an electric motor, it is not possible to clean the appliance properly, particularly in a dishwasher, and in particular it is not possible to sterilize the leading end carrying the tool that is to come into contact with successive preparations that are generally different. Unfortunately, the tool rotating at high speed acts as a pump providing upward suction. This means that in spite of the precautions taken concerning sealing, a small portion of the blended and chopped liquids rises inside the tube where it can often putrefy under the action of bacteria.